Just because they have gone dead and don't sound right doesn't mean that they should be thrown out. They are the same as the music wire (piano wire) that some people use - a bit harder to bend than brass wire, but they are also harder to accidentally bend if the loco or car they are mounted on falls over. As a bonus, they come in a number of sizes (most sets of strings have 3 or 4 plain strings and the rest are "wound", and the diameter is usually specified).

If you don't play guitar yourself, you probably know someone who does. Failing that, I'm sure that any music shop that sells guitars would give you some old ones they have replaced.